Work vehicle

ABSTRACT

An operator&#39;s compartment is located above a climbing device and has a door. A sensing unit recognizes an operator. A door driving unit automatically opens the door in response the sensing unit sensing the operator.

TECHNICAL FIELD

The present invention relates to a work vehicle, and particularly to awork vehicle having a climbing device.

BACKGROUND ART

A wheel loader having a climbing device is disclosed for example inJapanese Patent Laying-Open No 2008-008183 (see Patent Document 1). Inthe wheel loader described in this publication, an operator'scompartment (or a cab) having a door is disposed above the climbingdevice.

CITATION LIST Patent Document

PTD 1: Japanese Patent Laying-Open No. 2008-008183

SUMMARY OF INVENTION Technical Problem

In the wheel loader described in the above publication, the operator caneasily climb the climb device by climbing the climb device while holdinga handrail. However, it is difficult for the operator holding thehandrail to open the door, which is large, of the operator's compartmenton the climbing device. This makes it difficult for the operator to getinto the operator's compartment from the climbing device.

The present invention has been made in view of the above issue. Anobject of the present invention is to provide a work vehicle allowing anoperator to easily get into an operator's compartment from a climbingdevice.

Solution to Problem

A work vehicle of the present invention comprises a climbing device, anoperator's compartment, a sensing unit, and a door driving unit. Theoperator's compartment is located above the climbing device and has adoor. The sensing unit recognizes an operator. The door driving unitautomatically opens the door in response the sensing unit sensing theoperator.

In the work vehicle, the operator's compartment has a step directlyunder the door. An entire locus of opening and closing of the dooroverlaps with the step in a plan view.

In the work vehicle, the door is a foldaway door.

The work vehicle further comprises a storage unit and a control unit.The storage unit has operator information previously stored therein. Thecontrol unit controls the door driving unit based on a result ofcomparing sensed information of an operator sensed by the sensing unitwith the operator information stored in the storage unit.

In the work vehicle, the sensing unit senses that an operator steps onthe climbing device.

In the work vehicle, the door is automatically closed after the operatorgets out of the operator's compartment.

The work vehicle is further comprises a solar panel disposed on an uppersurface of the operator's compartment.

Advantageous Effect of Invention

According to the present invention, a door driving unit automaticallyopens a door in response a sensing unit sensing an operator, and theoperator can easily get in an operator's compartment from a climbingdevice.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view schematically showing a configuration of awheel loader in one embodiment of the present invention.

FIG. 2 is a schematic plan view showing an operation of opening andclosing a door used in the wheel loader according to one embodiment ofthe present invention.

FIG. 3 is a schematic perspective view showing an operation ofdeploying/retracting a climbing device used in the wheel loaderaccording to one embodiment of the present invention, as seen from aleft front side.

FIG. 4 is a schematic perspective view showing the operation ofdeploying/retracting the climbing device shown in FIG. 3 from a rightfront side.

FIG. 5 is a functional block diagram for illustrating an operation ofthe climbing device and the door in the wheel loader according to oneembodiment of the present invention.

FIG. 6 is a first flowchart indicating a door opening/closing operationand a climbing device retracting/deploying operation performed when anoperator gets in the vehicle.

FIG. 7 is a second flowchart indicating the door opening/closingoperation and the climbing device retracting/deploying operationperformed when the operator gets in the vehicle.

FIG. 8 is a third flowchart indicating the door opening/closingoperation and the climbing device retracting/deploying operationperformed when the operator gets in the vehicle.

FIG. 9 is a first flowchart indicating a door opening/closing operationand a climbing device retracting/deploying operation performed when theoperator gets out of the vehicle.

FIG. 10 is a second flowchart indicating the door opening/closingoperation and the climbing device retracting/deploying operationperformed when the operator gets out of the vehicle.

FIG. 11 is a schematic plan view showing an operation of opening andclosing a door in an exemplary variation used in a wheel loaderaccording to one embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

The present invention will now be described in an embodiment hereinafterwith reference to the drawings.

First, a configuration of a wheel loader as an example of a work vehiclein one embodiment of the present invention will be described withreference to FIG. 1, however, the present invention is applicable to awork vehicle, such as a hydraulic excavator, a bulldozer and the like,comprising a cab having a door opening and closing mechanism.

In this example, a positional relationship of each part will bedescribed with reference to an operator seated on an operator's seat ina cab 30. A frontward/rearward direction is a directionfrontwardly/rearwardly of the operator seated on the operator's seat. Arightward/leftward direction is a direction rightwardly/leftwardly ofthe operator seated on the operator's seat. An upward/downward directionis a direction upwardly/downwardly of the operator seated on theoperator's seat.

A direction which is opposite to the operator seated on the operator'sseat is a frontward direction, and a direction opposite to the frontwarddirection is a rearward direction. A right side of the operator seatedon the operator's seat facing frontward is a rightward direction, and aleft side of the operator seated on the operator's seat facing frontwardis a leftward direction. A side closer to the feet of the operatorseated on the operator's seat is a lower side and a side closer to thehead of the operator seated on the operator's seat is an upper side.

FIG. 1 is a perspective view schematically showing a configuration of awheel loader according to one embodiment of the present invention. Asshown in FIG. 1, a wheel loader 40 according to the present embodimentmainly includes a front frame 31, a rear vehicular body 32, a workimplement 33, and a climbing device (or an access system) 20. A frontwheel 34 a is attached to each of opposite side portions of front frame31. A rear wheel 34 b is attached to each of opposite side portions ofrear vehicular body 32.

Front frame 31 and rear vehicular body 32 are attached by a center pin(not shown) so as to be able to swing right and left. Front frame 31 andrear vehicular body 32 constitute an articulated structure.

Specifically, front frame 31 and rear vehicular body 32 are coupled by apair of right and left steering cylinders (not shown). As the right andleft steering cylinders extend and contract, front frame 31 and rearvehicular body 32 swing right and left about the center pin and are thussteered. Front frame 31 and rear vehicular body 32 configure a vehicularbody of wheel loader 40.

Work implement 33 is attached in front of front frame 31. Work implement33 has a pair of booms 33 a, a bucket 33 b, a pair of boom cylinders(not shown), a bell crank 33 d, a bucket cylinder 33 e, and a link 33 f.

Boom 33 a has a proximal end portion attached to front frame 31 so thatboom 33 a is swingable as desired relative to front frame 31. Bucket 33b is swingably attached to a distal end portion of boom 33 a. The boomcylinders couple front frame 31 and boom 33 a together. As the boomcylinders extend and contract, boom 33 a swings relative to front frame31.

Bell crank 33 d has a substantially center portion supported by boom 33a so that bell crank 33 d is swingable as desired relative to boom 33 a.Bucket cylinder 33 e couples a proximal end portion of bell crank 33 dand front frame 31. Link 33 f couples a distal end portion of bell crank33 d and bucket 33 b. As bucket cylinder 33 e extends and contracts,bucket 33 b swings relative to boom 33 a.

An engine compartment 32 b is disposed behind rear vehicular body 32. Ahydraulic oil tank 32 a is disposed in front of engine compartment 32 b.Rear vehicular body 32 has an operator's compartment (e.g., a cab) 30 infront of hydraulic oil tank 32 a. Operator's compartment 30 constitutesa space for the operator to enter the compartment and operate wheelloader 40.

Operator's compartment 30 is provided with an opening 30 a for a door.Opening 30 a for the door connects an internal space of operator'scompartment 30 to an external space. Operator's compartment 30 has adoor 10. Door 10 is configured to be able to open and close opening 30 afor the door.

A solar panel 35 is disposed on an upper portion of operator'scompartment 30. Solar panel 35 employs a solar cell to convert solarlight directly into electric power to thus generate electric power. Astep 30 b is attached to a side portion of operator's compartment 30below opening 30 a for the door.

Hereinafter, a configuration of door 10 in wheel loader 40 of thepresent embodiment will be described with reference to FIG. 2.

FIG. 2 is a schematic plan view showing an operation of opening andclosing a door used in a wheel loader according to one embodiment of thepresent invention. As shown in FIG. 2, door 10 is a foldaway(accordion-type) door, for example.

Door 10 has a plurality of (e.g., two) door panels 10 a and 10 b. Doorpanels 10 a, 10 b each have a frontward/rearward dimension substantiallyequal to a dimension obtained by dividing a frontward/rearward dimensionof opening 30 a for the door into a plurality (e.g., two). Door panels10 a, 10 b each have an upward/downward dimension substantially equal toan upward/downward dimension of opening 30 a for the door.

Door panel 10 a is disposed rearwardly of door panel 10 b. Door panel 10a has a rear end portion supported with respect to operator'scompartment 30 rotatably about a rotation shaft 10 d. Thus, door panel10 a is rotatable about rotation shaft 10 d to be movable between aposition in which opening 30 a for the door is closed, as indicated by asolid line, and a position in which door panel 10 a has a front endportion projecting toward a space external to operator's compartment 30,as indicated by a broken line.

The front end portion of door panel 10 a and a rear end portion of doorpanel 10 b are coupled together with a rotation shaft 10 c interposed.Door panel 10 a and door panel 10 b are relatively rotatable aboutrotation shaft 10 c. Thus, door panels 10 a and 10 b are mutuallyrotatable between a state in which they are aligned with each otherlinearly in the frontward/rearward direction and a state in which theyare mutually bent as indicated by a broken line.

A sliding piece 10 e is attached to a front end portion of door panel 10b for example. Sliding piece 10 e is engaged with a guide rail 30 aaslidably along guide rail 30 aa. Guide rail 30 aa is provided in thevicinity of opening 30 a for the door of operator's compartment 30.Further, door panel 10 b is supported by operator's compartment 30rotatably about sliding piece 10 e. Thus, door panel 10 b is movablebetween a position in which opening 30 a for the door is closed, asindicated by a solid line, and a position in which door panel 10 b movesrearward and also has the rear end portion projecting toward a spaceexternal to operator's compartment 30, as indicated by a broken line.

Thus, door 10 is movable between a state in which opening 30 a for thedoor is closed, as indicated by a solid line, and a state in whichopening 30 a for the door is opened, as indicated by a broken line. Door10 in the state in which opening 30 a for the door is opened has doorpanels 10 a and 10 b mutually bent and thus configuring a folded shape.

Door 10 can be opened and closed automatically. In order to be able toautomatically open and close door 10, a door driving unit 11 isconnected to door 10. Door driving unit 11 has one end portion attachedto operator's compartment 30 rotatably about a rotation shaft 11 a. Doordriving unit 11 has the other end portion attached to door panel 10 brotatably about a rotation shaft 11 b. Rotation shaft 11 b is disposedat the front end portion of door panel 10 b in the vicinity of slidingpiece 10 e in a plan view. Rotation shaft 11 b is disposed offset fromdoor panel 10 b toward the interior of the operator's compartment.Specifically, door panel 10 b has a bent portion 10 b 1 that is bent soas to extend toward the interior of the operator's compartment with door10 closed, and the rotation shaft 11 b is disposed at bent portion 10 b1. Rotation shaft 11 b may be formed in one piece with sliding piece 10e.

Driving door driving unit 11 (for example, extending and contracting anelectric actuator) allows an operation to open and close door 10. Forexample, when an electric actuator serving as door driving unit 11extends, door 10 closes opening 30 a for the door, and when the electricactuator contracts, door 10 opens opening 30 a for the door. Incontrast, door 10 and door driving unit 11 may be configured such thatwhen the electric actuator serving as door driving unit 11 extends, door10 may open opening 30 a for the door, and when the electric actuatorcontracts, door 10 may close opening 30 a for the door. Note that theelectric actuator may be replaced with a hydraulic cylinder.

In the present embodiment, wheel loader 40 further includes a controlunit CR, a sensing unit SE1, and a storage unit MR. Control unit CR isconnected to door driving unit 11. Control unit CR serves to control anoperation of door driving unit 11. Control unit CR for example includesa drive control unit, and the drive control unit drivably controls theelectric actuator serving as door driving unit 11. When the electricactuator is replaced with a hydraulic cylinder, control unit CR forexample includes a hydraulic pump and a control valve, and the hydrauliccylinder is drivably controlled by an operation of the hydraulic pumpand control valve.

Sensing unit SE1 is connected to control unit CR. Sensing unit SE1serves to sense an operator. In response to sensing unit SE1 sensing theoperator, control unit CR controls an operation of door driving unit 11.

By an operation of door driving unit 11, door 10 is operated toautomatically open opening 30 a for the door. Furthermore, by anoperation of door driving unit 11, door 10 is operated to automaticallyclose opening 30 a for the door. For example, sensing unit SE1 may be acamera, a microphone, a contact sensor, a load sensor, a smart keyreceiver, and the like singly or in any combination thereof.

The camera as sensing unit SE1 is attached to an upper portion ofoperator's compartment 30, for example. The contact sensor is attachedfor example to climbing device 20 at a handrail portion 22. When anoperator who is going to get in the vehicle touches handrail portion 22of climbing device 20, the contact sensor can sense the operator. Theload sensor is attached to climbing device 20 for example. When theoperator steps on climbing device 20, the load sensor can sense theoperator. The smart key receiver makes a pair with a smart key.

The smart key is a portable wireless key, and the work vehicle and thesmart key are provided with a short-distance wireless function and door10 is locked and unlocked by wireless communications between the workvehicle and the smart key. When the smart key receiver senses the smartkey carried by the operator with him/her, the operator can be sensed.

Sensing unit SE1 may sense the operator before the operator steps onclimbing device 20, or may sense the operator after the operator stepson climbing device 20.

Storage unit MR is connected to control unit CR. Storage unit MR hasoperator information previously stored therein. Control unit CR maycontrol door driving unit 11 based on a result of comparing sensedinformation of the operator sensed by sensing unit SE1 with the operatorinformation stored in storage unit MR. This allows individualauthentication of an operator who is going to get in wheel loader 40.

When sensing unit SE1 is for example a camera, control unit CR comparesan image of the operator picked up by the camera with the operatorinformation (or an image) stored in storage unit MR. If as a result ofthe comparison it is determined that the operator who is going to get inthe vehicle is a previously registered operator, door driving unit 11may be driven to control and thus open door 10.

When sensing unit SE1 is for example a microphone, control unit CRcompares a voice print of the operator collected by the microphone withthe operator information (or a voice print) stored in storage unit MR.If as a result of the comparison it is determined that the operator whois going to get in the vehicle is a previously registered operator, doordriving unit 11 may be driven to control and thus open door 10.

When sensing unit SE1 is for example a contact sensor, control unit CRcompares a feature of the operator obtained by the sensor with theoperator information stored in storage unit MR. If as a result of thecomparison it is determined that the operator who is going to get in thevehicle is a previously registered operator, door driving unit 11 may bedriven to control and thus open door 10.

When sensing unit SE1 is for example a smart key receiver, control unitCR compares information of a smart key received by the smart keyreceiver (or sensed information of the operator) with the operatorinformation (or information of the smart key) stored in storage unit MR.If as a result of the comparison it is determined that the smart keymatches the information of the smart key previously registered, doordriving unit 11 may be driven to control and thus open door 10.

Hereinafter, a configuration of climbing device 20 in wheel loader 40 ofthe present embodiment will be described with reference to FIGS. 3 and4.

FIGS. 3 and 4 are schematic perspective views showing an operation ofdeploying/retracting the climbing device used in the wheel loaderaccording to one embodiment of the present invention, as seen from aleft front side and a right front side, respectively. Note that in FIGS.3 and 4, a pair of right and left handrail portions 22, a pair of rightand left side members 21 d, and a pair of right and left pivotingmembers 21 g have only one handrail portion 22, one side member 21 d,and one pivoting member 21 g, respectively, shown and have the otherhandrail portion 22, the other side member 21 d, and the other pivotingmember 21 g, respectively, unshown. Further, in FIGS. 3 and 4, adeployed position is indicated by a solid line, and a retracted positionis indicated by a broken line. Directions rightwardly and leftwardly ofa climbing device body 21 included in climbing device 20 correspond todirections frontwardly and rearwardly of wheel loader 40.

As shown in FIGS. 3 and 4, climbing device 20 mainly includes climbingdevice body 21, a pair of right and left handrail portions (a handrail)22, and a support member 23.

Climbing device body 21 has a pair of right and left first end portions21A and a pair of right and left second end portions 21B. Climbingdevice body 21 is attached to the vehicular body of wheel loader 40 atfirst end portion 21A so as to be driven rotatably with respect to thevehicular body.

In FIGS. 3 and 4, as has been set forth above, the pair of right andleft side members 21 d has only one side member 21 d alone shown.Accordingly, in FIGS. 3 and 4, the pair of right and left first endportions 21A has only one first end portion 21A shown, and the pair ofright and left second end portions 21B has only one second end portion21B shown.

As climbing device body 21 is rotatably driven, it can assume aretracted position and a deployed position (or a position for use). Inthe retracted position, climbing device body 21 is erected such thatfirst end portion 21A is positioned above and second end portion 21B ispositioned below. In the deployed position, climbing device body 21 isinclined such that second end portion 21B is located outer than firstend portion 21A on a lateral side of the vehicle.

Climbing device body 21 mainly has a plurality of step portions 21 a, apair of right and left side members 21 d, a connection member 21 e, anauxiliary link member 21 f, and a pivoting member 21 g. The plurality ofstep portions 21 a are each a portion serving as a step when theoperator climbs up and down climbing device body 21. The plurality ofstep portions 21 a are aligned upward/downward side by side.

Of the plurality of steps, an uppermost step portion 21 a 4 locatedclosest to first end portion 21A is connected to the vehicular body viathe pair of right and left pivoting members 21 g. Pivoting member 21 gis connected to uppermost step portion 21 a 4 rotatably about a rotationshaft 21 ga. Furthermore, pivoting member 21 g is connected to thevehicular body rotatably about a rotation shaft 21 gb.

The pair of right and left side members 21 d is connected to each of theplurality of step portions 21 a. The pair of right and left side members21 d sandwich the plurality of step portions 21 a. A ladder is composedof the plurality of step portions 21 a and the pair of right and leftside members 21 d.

The paired right and left side members 21 d each have a first member 21b and a second member 21 c. First member 21 b extends linearly. Firstmember 21 b has an upper end attached to step 30 b of operator'scompartment 30 rotatably about a rotation shaft 21 ba.

Second member 21 c has a linear tubular portion 21 ca and a projectingportion 21 cc. Tubular portion 21 ca is composed of a tube which has aninner diameter larger than an outer diameter of first member 21 b. Firstmember 21 b has a lower end partially inserted into tubular portion 21ca.

With first member 21 b inserted in tubular portion 21 ca of secondmember 21 c, second member 21 c can be slid relative to first member 21b. Such sliding can change an entire longitudinal length of first member21 b and second member 21 c (i.e., a length of side member 21 d). Whenclimbing device body 21 assumes the deployed position, side member 21 dis relatively long, whereas when climbing device body 21 assumes theretracted position, side member 21 d is relatively short.

The plurality of step portions 21 a have a first step portion 21 a 1, asecond step portion 21 a 2, and a third step portion 21 a 3. First stepportion 21 a 1 is a step portion of the plurality of step portions 21 adisposed at a side of first member 21 b closest to second end portion21B, and first step portion 21 a 1 is attached to first member 21 brotatably. Second step portion 21 a 2 is a step portion of the pluralityof step portions 21 a disposed at a side of second member 21 c closestto second end portion 21B, and second step portion 21 a 2 is attached tosecond member 21 c rotatably. Third step portion 21 a 3 is attached tosecond member 21 c between first step portion 21 a 1 and second stepportion 21 a 2 slidably and rotatably. In the present embodiment, twothird step portions 21 a 3 are disposed between first step portion 21 a1 and second step portion 21 a 2.

Note that any step portion 21 a connected to first member 21 b excludingfirst step portion 21 a 1 is connected to first member 21 b rotatably.

Third step portion 21 a 3 is connected by auxiliary link member 21 f toat least one of first step portion 21 a 1 and second step portion 21 a2. In the present embodiment, one of two third step portions 21 a 3 isconnected to first step portion 21 a 1 by auxiliary link member 21 f.Furthermore, the other of two third step portions 21 a 3 is connected tosecond step portion 21 a 2 by auxiliary link member 21 f. Furthermore,two third step portions 21 a 3 are also connected by auxiliary linkmember 21 f

Auxiliary link member 21 f has a so-called rhombic link mechanism. Therhombic link mechanism has a configuration in which four linking piecesare assembled in a rhombic shape so that the four linking pieces arerotatable relative to each other. When climbing device body 21 assumesthe deployed position, auxiliary link member 21 f linearly extends,whereas when climbing device body 21 assumes the retracted position,auxiliary link member 21 f is retracted in the form of a rhombus.Accordingly, when climbing device body 21 assumes the deployed position,first, second and third step portions 21 a 1, 21 a 2 and 21 a 3 arepositioned away from one another, whereas when climbing device body 21assumes the retracted position, first, second and third step portions 21a 1, 21 a 2 and 21 a 3 are positioned close to one another.

Tubular portion 21 ca of second member 21 c has an opening 21 cb formedin a longitudinal direction thereof. Projecting portion 21 cc isconnected to tubular portion 21 ca at a side of opening 21 cb closer tofirst end portion 21A. Projecting portion 21 cc projects sideway oftubular portion 21 ca. Connection member 21 e has one end portionrotatably supported by projecting portion 21 cc (or second member 21 c).Accordingly, one end portion of connection member 21 e connected toprojecting portion 21 cc is slidable relative to first member 21 b.

The pair of right and left handrail portions 22 is attached to sidemember 21 d of climbing device body 21. The pair of right and lefthandrail portions 22 has a gripping portion 22 a, a pair of link members22 e 1 and 22 e 2, and a coupling piece 22 b.

Gripping portion 22 a is a portion gripped by an operator climbing upand down climbing device body 21. The pair of link members 22 e 1 and 22e 2 support gripping portion 22 a to climbing device body 21. Grippingportion 22 a is supported by the pair of link members 22 e 1 and 22 e 2to side member 21 d such that gripping portion 22 a is parallel to sidemember 21 d.

Paired link members 22 e 1 and 22 e 2 each have a first link piece 22 cand a second link piece 22 d. Paired link members 22 e 1 and 22 e 2 eachhave first link piece 22 c attached to climbing device body 21rotatably.

More specifically, one link member 22 e 1 has first link piece 22 cattached to first member 21 b rotatably. The other link member 22 e 2also has first link piece 22 c attached to first member 21 b rotatably.The other link member 22 e 2 has first link piece 22 c attached to firstmember 21 b slidably along opening 21 cb of second member 21 c relativeto second member 21 c.

Paired link members 22 e 1 and 22 e 2 each have second link piece 22 dattached to first link piece 22 c and gripping portion 22 a rotatably.

Coupling piece 22 b has one end 22 b 1 and the other end 22 b 2.Coupling piece 22 b has one end 22 b 1 connected to one link member 22 e1 at a first connecting portion connecting first link piece 22 c andsecond link piece 22 d together. Coupling piece 22 b is rotatablerelative to both first link piece 22 c and second link piece 22 d of onelink member 22 e 1.

Coupling piece 22 b has the other end 22 b 2 connected to the other linkmember 22 e 2 at a second connecting portion connecting first link piece22 c and second link piece 22 d together. Coupling piece 22 b isrotatable relative to both first link piece 22 c and second link piece22 d of the other link member 22 e 2.

First member 21 b of side member 21 d, coupling piece 22 b, first linkpiece 22 c of one link member 22 e 1, and first link piece 22 c of theother link member 22 e 2 configure a first rectangular link mechanism.Furthermore, gripping portion 22 a, coupling piece 22 b, second linkpiece 22 d of one link member 22 e 1, and second link piece 22 d of theother link member 22 e 2 configure a second rectangular link mechanism.

Connection member 21 e has one end portion rotatably supported byprojecting portion 21 cc of second member 21 c. Connection member 21 ehas the other end portion attached to gripping portion 22 a togetherwith second link piece 22 d of the other link member 22 e 2 rotatably.

Connection member 21 e has the other end portion connected to aconnecting portion connecting gripping portion 22 a and second linkpiece 22 d of the other link member 22 e 2. Furthermore, connectionmember 21 e has a center portion connected to a connecting portionconnecting the three members of coupling piece 22 b, and first linkpiece 22 c and second link piece 22 d of the other link member 22 e 2.Thus, connection member 21 e is rotatable relative to gripping portion22 a, coupling piece 22 b, and first link piece 22 c of the other linkmember 22 e 2.

Handrail portion 22 operates in a manner engaged with a rotationoperation of climbing device body 21. When climbing device body 21assumes the deployed position, handrail portion 22 is in a raised state,whereas when climbing device body 21 assumes the retracted position,handrail portion 22 is in a folded state.

In the raised state, gripping portion 22 a assumes a first positiondistant from climbing device body 21. In the folded state, grippingportion 22 a assumes a second position closer to climbing device body 21than when in the raised state.

Climbing device body 21 is movable between the retracted position andthe deployed position by support member 23. Support member 23 has oneend portion 23A and the other end portion 23B. Support member 23 has oneend portion 23A attached to the vehicular body. Support member 23 hasthe other end portion 23B attached to second member 21 c rotatably. Adistance between one end portion 23A and the other end portion 23B ofsupport member 23 can be extended and contracted.

Support member 23 has a connection member 23 a, a driving member 23 b,and a fixture 23 c. Connection member 23 a is rotatably attached tosecond member 21 c. Fixture 23 c is attached to the vehicular body.Driving member 23 b can be extended and contracted, and is composed forexample of an electric actuator. Driving member 23 b may be composed ofa hydraulic cylinder rather than an electric actuator. As driving member23 b extends and contracts, a distance between the one end portion 23Aand the other end portion 23B of support member 23 can be extended andcontracted. Climbing device body 21 can thus be moved between theretracted position and the deployed position.

As shown in FIG. 4, control unit CR is connected to driving member 23 b.Control unit CR serves to control an operation of driving member 23 b.Control unit CR for example includes a drive control unit, and the drivecontrol unit drivably controls an electric actuator serving as drivingmember 23 b. When the electric actuator is replaced with a hydrauliccylinder, control unit CR for example includes a hydraulic pump and acontrol valve, and the hydraulic cylinder is drivably controlled by anoperation of the hydraulic pump and control valve.

A sensing unit SE2 is connected to control unit CR. When climbing devicebody 21 has its position changed from the retracted position to thedeployed position, a sensor for sensing that wheel loader 40 is stopped,a sensor for sensing that a parking switch is turned on, a sensor forsensing that a door opening/closing switch is turned on, a sensor forsensing that a switch operated to deploy climbing device body 21 isturned on, etc. are used singly or in any combination as sensing unitSE2.

Furthermore, when climbing device body 21 has its position changed fromthe deployed position to the retracted position, a load sensor for loadon driving member 23 b, a camera, a seating sensor provided inoperator's compartment 30 at the operator's seat for sensing that anoperator is seated, a seat belt sensor for sensing that a seat belt isfastened, a sensor for sensing that a key switch (an engine startingswitch) is turned on, etc. are used singly or in any combination assensing unit SE2.

Hereinafter, an operation of climbing device 20 will be described.Initially, the retracted position will be described with reference toFIG. 3 and FIG. 4.

As shown in FIGS. 3 and 4, in the retracted position, climbing devicebody 21 is erected such that first end portion 21A is positioned aboveand second end portion 21B is positioned below.

In the retracted position, support member 23 has driving member 23 b ina contracted state. As a result, first member 21 b has a considerableamount inserted in tubular portion 21 ca of second member 21 c, and sidemember 21 d is in a contracted state. Further, auxiliary link member 21f is in a rhombic shape and hence in a contracted state. Accordingly, adistance between first step portion 21 a 1 and second step portion 21 a2, a distance between second step portion 21 a 2 and third step portion21 a 3, and a distance between third step portions 21 a 3 are smallerthan a distance between step portions 21 a connected to first member 21b in the retracted position.

Furthermore, in the retracted position, side member 21 d and couplingpiece 22 b are inclined relative to first link piece 22 c of each of onelink member 22 e 1 and the other link member 22 e 2. Furthermore, sidemember 21 d and coupling piece 22 b are parallel, and first link pieces22 c are also parallel. Accordingly, the first rectangular linkmechanism (side member 21 d, coupling piece 22 b, and first link piece22 c) has a shape of a parallelogram other than an oblong.

Furthermore, in the retracted position, gripping portion 22 a andcoupling piece 22 b are inclined relative to second link piece 22 d ofeach of one link member 22 e 1 and the other link member 22 e 2.Furthermore, gripping portion 22 a and coupling piece 22 b are parallel,and second link pieces 22 d are also parallel. Accordingly, the secondrectangular link mechanism (gripping portion 22 a, coupling piece 22 b,and second link piece 22 d) has a shape of a parallelogram other than anoblong.

In the retracted position, one link member 22 e 1 has first link piece22 c and second link piece 22 d extending in mutually transversedirections. Furthermore, the other link member 22 e 2 has first linkpiece 22 c and second link piece 22 d extending in mutually transversedirections.

Thus the first and second rectangular link mechanisms each have a shapeof a parallelogram other than an oblong and are in a folded state. Inthe retracted position, gripping portion 22 a has an upper end 22 a 1located below step 30 b attached to operator's compartment 30.

When the retracted position is shifted to the deployed position, drivingmember 23 b is extended. Thus, climbing device body 21 assumes thedeployed position such that it is inclined such that second end portion21B is located outer than first end portion 21A on a lateral side of thevehicle.

On this occasion, side member 21 d rotates relative to the vehicularbody about rotation shafts 21 ba and 21 gb. Furthermore, second member21 c slides relative to first member 21 b, and side member 21 d extends.This increases a distance between first step portion 21 a 1 and secondstep portion 21 a 2, and auxiliary link member 21 f is deformed from arhombic shape to a linear shape.

As auxiliary link member 21 f is deformed into the linear shape, thirdstep portion 21 a 3 between first step portion 21 a 1 and second stepportion 21 a 2 also moves. This increases a distance between third stepportion 21 a 3 and first step portion 21 a 1, a distance between thirdstep portion 21 a 3 and second step portion 21 a 2, and a distancebetween third step portions 21 a 3.

Furthermore, as second member 21 c slides relative to first member 21 b,connection member 21 e is rotated relative to second member 21 c andthus raised. As connection member 21 e is raised, the other link member22 e 2 also has first link piece 22 c and second link piece 22 d rotatedrelative to second member 21 c and thus raised.

As connection member 21 e is thus raised, handrail portion 22 shiftsfrom the folded state to the raised state. Climbing device body 21 thusshifts from the retracted position to the deployed position.

In the deployed position, support member 23 has driving member 23 b inan extended state. As a result, first member 21 b has a shorter lengthinserted in tubular portion 21 ca of second member 21 c than when in theretracted position, and side member 21 d is in an extended state.

Further, auxiliary link member 21 f is in a linear shape and hence in anextended state. Accordingly, a distance between first step portion 21 a1 and third step portion 21 a 3, a distance between second step portion21 a 2 and third step portion 21 a 3, and a distance between third stepportions 21 a 3 are substantially equal to a distance between stepportions 21 a connected to the first member in the deployed position.

In the deployed position, side member 21 d and coupling piece 22 b aresubstantially orthogonal to first link piece 22 c of each of one linkmember 22 e 1 and the other link member 22 e 2. Furthermore, side member21 d and coupling piece 22 b are parallel, and first link pieces 22 care also parallel. Accordingly, the first rectangular link mechanism hasa substantially oblong shape.

Furthermore, in the deployed position, gripping portion 22 a andcoupling piece 22 b are substantially orthogonal to second link piece 22d of each of one link member 22 e 1 and the other link member 22 e 2.Furthermore, gripping portion 22 a and coupling piece 22 b are parallel,and second link pieces 22 d are also parallel. Accordingly, the secondrectangular link mechanism has a substantially oblong shape.

In the deployed position, one link member 22 e 1 has first link piece 22c and second link piece 22 d disposed collinearly. Furthermore, theother link member 22 e 2 has first link piece 22 c and second link piece22 d disposed collinearly.

When the deployed position is shifted to the retracted position, drivingmember 23 b is contracted. This causes an operation opposite to shiftingfrom the retracted position to the deployed position as described aboveand climbing device body 21 thus assumes the retracted position.

Hereinafter will be described how door 10 is controlled to be opened andclosed and how climbing device 20 is controlled to be contracted anddeployed when an operator gets in and out of wheel loader 40. Initially,a control applied when the operator gets in wheel loader 40 will bedescribed with reference to FIGS. 5-8.

FIG. 5 is a functional block diagram for illustrating an operation ofthe climbing device and the door in the wheel loader according to oneembodiment of the present invention. FIGS. 6-8 are flowcharts indicatinga door opening/closing operation and a climbing deviceretracting/deploying operation performed when the operator gets in thevehicle.

Wheel loader 40 is stopped and climbing device body 21 is in a deployedstate. In this state, as shown in FIG. 5 and FIG. 6, a sensor mounted onwheel loader 40 senses that an operator approaches wheel loader 40 orsteps on climbing device body 21, and personal authentication isperformed (step S1 a). This sensor is for example a camera, amicrophone, a contact sensor, or a smart key receiver.

When the sensor is for example a camera, control unit CR performsauthentication by comparing an image of the operator picked up by thecamera with operator information (or an image) stored in storage unitMR.

When the sensor is for example a microphone, control unit CR performsauthentication by comparing a voice print of the operator collected bythe microphone with the operator information (or a voice print) storedin storage unit MR.

When the sensor is for example a contact sensor provided to climbingdevice 20, control unit CR performs authentication by comparing afeature of the operator obtained by the sensor with the operatorinformation stored in storage unit MR.

When the sensor is for example a smart key receiver, control unit CRperforms authentication by comparing information of a smart key receivedby the smart key receiver (or sensed information of the operator) withthe operator information (or information of the smart key) stored instorage unit MR.

Whether or not the operator (or the smart key) matches the informationof the operator (or the smart key) stored in storage unit MR isdetermined by the above authentication (step S2 a).

As a result of the authentication, if the operator (or the smart key)does not match the operator (or the smart key) stored in storage unitMR, the operator is accordingly informed for example by a sound througha speaker, a buzzer sound, etc. (Step S3 a). As a result of theauthentication, if the operator (or the smart key) matches the operator(or the smart key) stored in storage unit MR, the operator isaccordingly informed for example by a sound through a speaker, a buzzersound, etc. (Step S4 a).

Thereafter, whether or not there is an obstacle within a range of anoperation of opening/closing door 10 is sensed by a sensor (e.g., acamera), and determined by control unit CR (step S5 a). When it isdetermined that there is an obstacle, the operator is notified by asound through a speaker, a buzzer sound, etc. that an operation to opendoor 10 cannot be performed (step S6 a).

When it is determined that there is no such obstacle, the operator isnotified by a sound through a speaker, a buzzer sound, etc. that anoperation to open door 10 is performed (step S7 a). Subsequently, doordriving unit 11 is activated to perform the operation to open door 10(step S8 a).

The operation to open door 10 is performed by retracting door drivingunit 11 (e.g., a hydraulic cylinder), as shown in FIG. 2.

Thereafter, whether or not there is a trouble in door driving unit 11 inopening and closing door 10 is sensed for example by the load sensor forload on the driving unit, and determined by control unit CR (step S8 a1). If there is no excessive load acting on door driving unit 11, theoperation to open door 10 is continued. If there is an excessive loadacting on door driving unit 11, door driving unit 11 is inactivated(step S8 a 2).

Then, control unit CR determines from a length of door drive unit 11 orthe like whether or not an operation of opening door 10 is completed(step S8 a 3). If the operation to open door 10 has not been completed,the operator is informed audibly or the like that the operation to opendoor 10 cannot be performed due to an excessive load (step S8 a 4).

Once the operation of opening door 10 has been completed, the operatoris notified accordingly (step S8 a 5). Once the operation of openingdoor 10 has been completed, the operator climbs climbing device 20 whileholding handrail portion 22, and after the operator has finishedclimbing climbing device 20, the operator enters operator's compartment30 through door 10 opened (i.e., gets in the vehicle).

As shown in FIGS. 5 and 7, whether or not the operator has got intooperator's compartment 30 is sensed by a getting-in sensor anddetermined by control unit CR (step S9 a). The getting-in sensor is forexample a camera, a load sensor for load on driving member 23 b, or thelike.

When the getting-in sensor is for example a camera, control unit CRdetermines whether or not the operator has got in the vehicle based onan image of the operator picked up by the camera. When the getting-insensor is for example a load sensor for load on driving member 23 b,control unit CR determines whether or not the operator has got in thevehicle based on a signal of the load sensor sensing a load received byclimbing device 20.

When it is determined that the operator has got in the vehicle, whetheror not the operator is under a safe condition is sensed by a statesensor and determined by control unit CR (step S10 a). The state sensoris for example a seating sensor for sensing that an operator is seated,a seat belt sensor for sensing that a seat belt is fastened, a switchoperated to retract/deploy climbing device 20, and/or the like.

When the state sensor is for example the seating sensor, control unit CRdetermines whether or not the operator is under a safe condition basedon a signal of the seating sensor sensing that the operator has seatedhimself/herself in the operator's seat.

When the state sensor is for example the seat belt sensor, control unitCR determines whether or not the operator is under a safe conditionbased on a signal of the seat belt sensor sensing that the operator hasfastened the seat belt.

When the state sensor is for example the switch operated toretract/deploy climbing device 20, control unit CR determines whether ornot the operator is under a safe condition based on a signal indicatingthat the switch is turned on.

When it is determined that the operator is under a safe condition, then,whether or not there is an obstacle within a range of an operation ofclosing door 10 is sensed by a sensor (e.g., a camera), and determinedby control unit CR (step S11 a). When it is determined that there is anobstacle, the operator is notified by a sound through a speaker, abuzzer sound, etc. that an operation to close door 10 cannot beperformed (step S12 a).

When it is determined that there is no such obstacle, the operator isnotified by a sound through a speaker, a buzzer sound, etc. that theoperation to close door 10 is performed (step S13 a). Subsequently, doordriving unit 11 is activated to perform the operation to close door 10(step S14 a).

The operation to close door 10 is performed by extending door drivingunit 11 (e.g., a hydraulic cylinder), as shown in FIG. 2.

Subsequently, whether or not an excessive load acts on door driving unit11 is sensed by the load sensor, and determined by control unit CR (stepS15 a). When an excessive load is acting on door driving unit 11, theoperation to close door 10 is stopped (step S17 a), and the operator isnotified that the operation to close door 10 cannot be performed (stepS18 a). If there is no excessive load acting on door driving unit 11,the operation to close door 10 is continued (step S16 a). Once door 10has completely been closed, the operator is notified accordingly.

As shown in FIGS. 5 and 8, whether or not there is an obstacle within arange on climbing device 20 and from the deployed position thereof tothe retracted position thereof is sensed by a sensor (e.g., a camera),and determined by control unit CR (step S19 a). When it is determinedthat there is an obstacle, the operator is notified by a sound through aspeaker, a buzzer sound, etc. that an operation to retract climbingdevice 20 cannot be performed (step S20 a).

When it is determined that there is no obstacle, the operator isnotified by a sound through a speaker, a buzzer sound, etc. that theoperation to retract climbing device 20 is performed (step S21 a).Subsequently, climbing device 20 is actuated and thus shifted to theretracted position (step S22 a). A state of shifting of climbing device20 to the retracted position is displayed on a monitor (a displaydevice) attached to wheel loader 40. Note that a setting is done suchthat locking of work implement 33 and a parking brake are not set offbefore climbing device 20 assumes the retracted position.

Whether climbing device 20 has assumed the retracted position isdetermined (step S23 a). Once climbing device 20 has assumed theretracted position, the operator is accordingly notified by a soundthrough a speaker, a buzzer sound, etc. (step S24 a). Furthermore, onceclimbing device 20 has assumed the retracted position, locking of workimplement 33 and the parking brake can be set off (step S25 a).

Hereinafter, a control applied when the operator gets out of wheelloader 40 will be described with reference to FIGS. 5, 9 and 10.

FIGS. 9 and 10 are flowcharts indicating a door opening/closingoperation and a climbing device retracting/deploying operation performedwhen the operator gets out of the vehicle.

As shown in FIGS. 5 and 9, initially, wheel loader 40 stops (step S1 b).In this state, operator's compartment 30 has door 10 closed and climbingdevice 20 assumes the retracted position.

Whether the parking brake is ON and locking the work implement is ON isdetermined (step S2 b). When the parking brake and locking the workimplement are not both ON, the operator is accordingly notified by asound through a speaker, a buzzer sound, etc. (step S3 b).

When the parking brake and locking the work implement are both ON,whether or not there is an obstacle within a range from the retractedposition of climbing device 20 to the deployed position thereof issensed by a sensor (e.g., a camera), and determined by control unit CR(step S4 b). In doing so, at least one of: whether a getting-out switchis turned on/off; a result of sensing by the seating sensor; and aresult of sensing by the seat belt sensor, is determined. When it isdetermined that there is no obstacle and when the getting-out switch isturned on, the seating sensor senses that the operator is not seated inthe operator's seat, or the seat belt sensor senses that the seat beltis not fastened, the operator is informed, for example by a sound ofthrough a speaker, a buzzer sound, or the like, that climbing device 20is deployed from the retracted position to the deployed position (stepS5 b).

Subsequently, climbing device 20 is deployed from the retracted positionto the deployed position (step S6 b). Whether deploying climbing device20 ends is determined (step S7 b). When deploying climbing device 20ends, the operator is notified, for example by a sound of through aspeaker, a buzzer sound, or the like, that an operation to open door 10starts (step S8 b). Subsequently, the operation to open door 10 isperformed (step S9 b).

The operation to open door 10 is performed by retracting door drivingunit 11 (e.g., a hydraulic cylinder), as shown in FIG. 2.

As shown in FIGS. 5 and 10, whether or not there is an obstacle within arange of an operation of opening door 10 or whether or not there is anexcessive load acting on the operation to open door 10 is sensed by asensor (e.g., a camera or a load sensor), and determined by control unitCR (step S10 b). When it is determined that there is an obstacle or anexcessive load, the operation to open door 10 is stopped (step S12 b),and the operator is notified by a sound through a speaker, a buzzersound, etc. that door 10 cannot be opened (step S13 b).

When it is determined that there is no obstacle or excessive load, theoperation to open door 10 is continued and door 10 is thus opened (stepS11 b). When the operation of opening door 10 is completed, the operatorgets out of operator's compartment 30 through door 10 opened (and thusgets out of the vehicle) and climbs down climbing device 20. At thetime, whether or not the operator has got out of operator's compartment30 is sensed by a sensor, and determined by control unit CR (step S14b). This sensor is for example a camera, a load sensor for load ondriving member 23 b, a smart key or the like.

When the sensor is for example a camera, control unit CR determineswhether or not the operator has got out of the vehicle based on an imageof the operator picked up by the camera. When the sensor is for examplea load sensor for load on driving member 23 b, control unit CRdetermines whether or not the operator has got out of the vehicle basedon a signal of the load sensor sensing a load received by climbingdevice 20. When the sensor is for example a smart key, control unit CRdetermines whether or not the operator has got out of the vehicle inresponse to a smart key receiver sensing that a smart key carried by theoperator gets out of operator's compartment 30.

When it is determined that the operator has got out of the vehicle,whether or not there is an obstacle within a range of an operation ofclosing door 10 is sensed by a sensor (e.g., a camera), and determinedby control unit CR (step S15 b). When it is determined that there is anobstacle, the operator is notified by a sound through a speaker, abuzzer sound, etc. that the operation to close door 10 cannot beperformed (step S16 b).

When it is determined that there is no such obstacle, the operator isnotified by a sound through a speaker, a buzzer sound, etc. that theoperation to close door 10 is performed (step S17 b). Subsequently, doordriving unit 11 is actuated to perform the operation to close door 10(step S18 b).

The operation to close door 10 is performed by extending door drivingunit 11 (e.g., a hydraulic cylinder), as shown in FIG. 2.

Thereafter, whether or not there is an obstacle within a range of anoperation of closing door 10 or whether or not there is an excessiveload acting on the operation to close door 10 is sensed by a sensor(e.g., a camera or a load sensor), and determined by control unit CR(step S19 b). When it is determined that there is an obstacle or anexcessive load, the operation to close door 10 is stopped (step S21 b),and the operator is notified by a sound through a speaker, a buzzersound, etc. that door 10 cannot be closed (step S22 b).

When it is determined that there is no obstacle or excessive load, theoperation to close door 10 is continued and door 10 is thus closed (stepS20 b).

As shown in FIG. 9, when it is determined that there is an obstacle instep S4 b, whether climbing device 20 can be deployed in asmall-deployment mode is determined (step S23 b). if climbing device 20cannot be deployed in the small-deployment mode, the operator isaccordingly notified for example by a sound of through a speaker, abuzzer sound, or the like (step S24 b).

If climbing device 20 can be deployed in the small-deployment mode, theoperator is accordingly notified for example by a sound of through aspeaker, a buzzer sound, or the like (step S25 b). Subsequently,shifting to the small-deployment mode is done (step S26 b).

When climbing device 20 is deployed in the small-deployment mode,whether or not there is an obstacle within a range of a small-deploymentoperation or whether or not there is an excessive load acting on theoperation to open door 10 is sensed by a sensor (e.g., a camera or aload sensor), and determined by control unit CR (step S27 b). When it isdetermined that there is an obstacle or an excessive load, thesmall-deployment operation is stopped (step S29 b) and the operator isnotified by a sound through a speaker, a buzzer sound, etc. that thesmall-deployment operation cannot be performed (step S30 b). When it isdetermined that there is no obstacle or excessive load, thesmall-deployment operation is continued and climbing device 20 attains asmall-deployment state (step S28 b).

Note that the climbing device is deployed/retracted by turning on/off aswitch operated to deploy/retract the climbing device for example.

Hereinafter, an exemplary variation of door 10 will described withreference to FIG. 11.

FIG. 11 is a schematic plan view showing an operation of opening andclosing a door in an exemplary variation used in a wheel loaderaccording to one embodiment of the present invention.

While in the above embodiment a case has been described in which door 10is a foldaway door 10, door 10 according to the present embodiment maybe a door in any type that recognizes an operator and is automaticallyopened (or closed). For example, as shown in FIG. 11, door 10 may be aslidable door. Slidable door 10 is composed of a single plate forexample. When this door 10 moves in the frontward/rearward direction,opening 30 a for the door can be opened/closed. A sliding operation ofdoor 10 is performed by a drive unit AC. Drive unit AC may be ahydraulic cylinder or may be a motor or the like.

Except for the above, slidable door 10 has a configuration substantiallyidentical to that of foldaway door 10 shown in FIG. 2, and accordingly,identical components are identically denoted and will not be describedredundantly.

While in the above embodiment a case has been described in which whetheror not an operator has got out of operator's compartment 30 (i.e.,whether or not the operator has got out of the vehicle) is sensed and anoperation is performed to automatically close door 10, whether theoperator has moved away from climbing device 20 may be sensed and anoperation to automatically close door 10 may accordingly be performed.

A function and effect of the present embodiment will be described.

According to the present embodiment, as shown in FIG. 2, door drivingunit 11 is provided which automatically opens door 10 in response tosensing unit SE1 sensing an operator. Therefore, it is unnecessary forthe operator to manually open large door 10 of operator's compartment 30while holding handrail portion 22 on climbing device body 21. Therefore,it is easy for the operator to get in operator's compartment 30 fromclimbing device 20.

Further, according to the present embodiment, as shown in FIG. 2, theentire locus of opening and closing of door 10 overlaps in a plan viewwith step 30 b fixed to operator's compartment 30. Therefore, when door10 is opened/closed, door 10 will never stick out of step 30 b in a planview. This can prevent door 10 from colliding against an operator onclimbing device body 21 while the door is being opened/closed.

Furthermore, according to the present embodiment, as shown in FIG. 2,door 10 is a foldaway door. Accordingly, when door 10 is opened/closed,door 10 can be easily prevented from sticking out of step 30 b in a planview.

Furthermore, in the present embodiment, as shown in FIG. 2, control unitCR controls door driving unit 11 based on a result of comparing sensedinformation of an operator sensed by sensing unit SE1 with operatorinformation stored in storage unit MR. This allows the operator to besubjected to personal authentication.

Furthermore, according to the present embodiment, sensing unit SE1senses that an operator steps on climbing device 20. This allows door 10to be opened at a time point when the operator steps on the climbingdevice.

Furthermore, according to the present embodiment, door 10 isautomatically closed after the operator gets out of operator'scompartment 30. Therefore, it is unnecessary for the operator tomanually close large door 10 of operator's compartment 30 while theoperator gets out of operator's compartment 30 and is present onclimbing device body 21. The operator can easily get out of operator'scompartment 30 to climbing device 20.

Furthermore, according to the present embodiment, as shown in FIG. 1,solar panel 35 is disposed on an upper surface of operator's compartment30. As a result, even when wheel loader 40 is stopped with the enginestopped, solar panel 35 can generate electric power, which allows an airconditioner to operate and air conditioning to be done in operator'scompartment 30.

Furthermore, according to the present embodiment, as shown in FIG. 3 andFIG. 4, handrail portion 22 in the deployed position is in a raisedstate in which gripping portion 22 a is moved away from climbing devicebody 21, and handrail portion 22 in the retracted position is in afolded state in which gripping portion 22 a approaches climbing devicebody 21. As handrail portion 22 is thus folded in the retractedposition, a dimension of handrail portion 22 projecting outward indirections rightwardly and leftwardly of wheel loader 40 can be limitedto be small. This can prevent handrail portion 22 otherwise projectingsideways in the retracted position from interfering with an obstacle.

Furthermore, according to the present embodiment, as shown in FIG. 3, inthe retracted position, gripping portion 22 a has upper end 22 a 1located below step 30 b. Therefore it is easy in the retracted positionto accommodate climbing device 20 within an area directly under step 30b. This suppresses projection of climbing device 20 in a plan viewoutwardly of step 30 b in directions rightwardly and leftwardly of wheelloader 40. This can prevent handrail portion 22 in the retractedposition from interfering with an obstacle.

Furthermore, according to the present embodiment, as shown in FIG. 3 andFIG. 4, handrail portion 22 has gripping portion 22 a, coupling piece 22b, and a pair of link members 22 e 1 and 22 e 2, and these partsconfigure a rectangular link mechanism. Handrail portion 22 can befolded by deforming this rectangular link mechanism.

Furthermore, according to the present embodiment, as shown in FIG. 3 andFIG. 4, side member 21 d has first member 21 b rotatably supported bythe vehicular body and second member 21 c attached to first member 21 bslidably relative thereto. By sliding second member 21 c relative tofirst member 21 b, side member 21 d can be changed in length.Accordingly, in the deployed position, side member 21 d can be extendedto be long from a vicinity of the ground to a high place. Further, inthe retracted position, by shortening side member 21 d, an appropriatespace can be ensured between second end portion 21B of the climbingdevice body and the ground.

Further, the other link member 22 e 2 has first link piece 22 c attachedto first member 21 b rotatably to be slidable relative to second member21 c. When first member 21 b slides relative to second member 21 c,first link piece 22 c of the other link member 22 e 2 is also slidablerelative to second member 21 c, and handrail portion 22 canappropriately function as a link mechanism.

Furthermore, according to the present embodiment, as shown in FIG. 3 andFIG. 4, connection member 21 e has one end portion rotatably supportedby second member 21 c, and the other end portion attached to grippingportion 22 a rotatably together with second link piece 22 d of the otherlink member 22 e 2. Accordingly, as second member 21 c slides relativeto first member 21 b, connection member 21 e is rotated relative tosecond member 21 c and thus raised or inclined and thus collapsed. Asconnection member 21 e is raised or inclined and thus collapsed, theother link member 22 e 2 also has second link piece 22 d rotatedrelative to second member 21 c and thus raised or inclined and thuscollapsed. Handrail portion 22 can thus be shifted between the raisedstate and the folded state.

Furthermore, according to the present embodiment, as shown in FIG. 3 andFIG. 4, support member 23 has one end portion 23A attached to thevehicular body, and the other end portion 23B attached to second member21 c rotatably. Furthermore, a distance between one end portion 23A andthe other end portion 23B can be extended and contracted by drivingmember 23 b. By using driving member 23 b to extend/contract supportmember 23, second member 21 c can be slid relative to first member 21 b,and climbing device body 21 can be shifted between the retractedposition and the deployed position.

Furthermore, according to the present embodiment, as shown in FIG. 3 andFIG. 4, support member 23 includes driving member 23 b allowing adistance between one end portion 23A and the other end portion 23B to beextended and contracted. Driving member 23 b allows climbing device body21 to be automatically shifted between the retracted position and thedeployed position.

Furthermore, according to the present embodiment, as shown in FIG. 3 andFIG. 4, a plurality of step portions 21 a have a first step portion 21 a1, a second step portion 21 a 2, and a third step portion 21 a 3. Firststep portion 21 a 1 is a step portion of the plurality of step portions21 a attached to a side of first member 21 b closest to second endportion 21B. Second step portion 21 a 2 is a step portion of theplurality of step portions 21 a attached to a side of second member 21 cclosest to second end portion 21B. Third step portion 21 a 3 is attachedto second member 21 c between first step portion 21 a 1 and second stepportion 21 a 2 slidably. Accordingly, when second member 21 c slidesrelative to first member 21 b, then, engaged with the sliding, thirdstep portion 21 a 3 can also be slid relative to second member 21 c.

Furthermore, when second member 21 c slides relative to first member 21b, then, in response to the amount of the sliding, a distance betweenthird step portion 21 a 3 and first step portion 21 a 1, a distancebetween third step portion 21 a 3 and second step portion 21 a 2, and adistance between third step portions 21 a 3 vary. Furthermore, accordingto the present embodiment, as shown in FIG. 3 and FIG. 4, an auxiliarylink member 21 f is provided: between third step portion 21 a 3 andfirst step portion 21 a 1; between third step portion 21 a 3 and secondstep portion 21 a 2; and between third step portions 21 a 3. Auxiliarylink member 21 f allows a distance between third step portion 21 a 3 andfirst step portion 21 a 1, a distance between third step portion 21 a 3and second step portion 21 a 2, and a distance between third stepportions 21 a 3 to be adjusted as appropriate.

It should be understood that the embodiments disclosed herein have beendescribed for the purpose of illustration only and in a non-restrictivemanner in any respect. The scope of the present invention is defined bythe terms of the claims, rather than the description above, and isintended to include any modifications within the meaning and scopeequivalent to the terms of the claims.

REFERENCE SIGNS LIST

10: door; 20: climbing device; 10 a, 10 b: door panel; 10 c, 10 d, 11 a,11 b, 21 ba rotation shaft; 10 e: sliding piece; 11: door driving unit;21: climbing device body; 21 a: step portion; 21 a 1: first stepportion; 21 a 2: second step portion; 21 a 3: third step portion; 21 a4: uppermost step portion; 21 b: first member; 21 c: second member; 21ca: tubular portion; 21 cb: opening; 21 cc: projecting portion; 21 d:side member; 21 e, 23 a:

connection member; 21 f: auxiliary link member; 21 g: pivoting member;21A: first end portion; 21B: second end portion; 22: handrail portion;22 a: gripping portion; 22 a 1: upper end; 22 b: coupling piece; 22 b 1:one end; 22 b 2: the other end; 22 c: first link piece; 22 d: secondlink piece; 22 e 1: one link member; 22 e 2: the other link member; 23:support member; 23A: one end portion; 23B: the other end portion; 23 b:driving member; 23 c: fixture; 30: operator's compartment; 30 a: openingfor door; 30 aa: guide rail; 30 b: step; 31: front frame; 32: rearvehicular body; 32 a: hydraulic oil tank; 32 b: engine compartment; 33:work implement; 33 a: boom; 33 b: bucket; 33 d: bell crank; 33 e: bucketcylinder; 33 f link; 34 a: front wheel; 34 b: rear wheel; 35: solarpanel; 40: wheel loader; AC: drive unit; CR: control unit; MR: storageunit; SE1, SE2: sensing unit.

1. A work vehicle comprising: a climbing device; an operator'scompartment located above the climbing device and having a door; asensing unit configured to recognize an operator; and a door drivingunit configured to automatically open the door in response the sensingunit sensing the operator.
 2. The work vehicle according to claim 1,wherein the operator's compartment has a step directly under the door,and an entire locus of opening and closing of the door overlaps with thestep in a plan view.
 3. The work vehicle according to claim 1, whereinthe door is a foldaway door.
 4. The work vehicle according to claim 1,further comprising: a storage unit configured to previously storeoperator information; and a control unit configured to control the doordriving unit based on a result of comparing sensed information of theoperator sensed by the sensing unit with the operator information storedin the storage unit.
 5. The work vehicle according to claim 1, whereinthe sensing unit senses that the operator steps on the climbing device.6. The work vehicle according to claim 1, wherein the door automaticallycloses after the operator has got out of the operator's compartment. 7.The working vehicle according to claim 1, further comprising a solarpanel disposed on an upper surface of the operator's compartment.